Pangaea began to break apart about 225 million years ago due to geological processes related to plate tectonics, which eventually spread Earth's landmasses into the continents we see today.

The supercontinent's pieces can be reassembled by tracing ancient mountain belts and other geologic patterns—such as the Appalachian Mountains, which are geologically related to mountains of England and Scandinavia.

But "we see older mountain belts suggesting that all the continents came together in the past to make other supercontinents," Loewy said.

Some of these features appear to be traces of Pangaea's predecessor, Rodinia, a supercontinent that contained most of the word's landmasses from about 1.1 billion to 750 million years ago. (Also see "Earliest Animals Were Sea Sponges, Fossils Hint.")

Rock Matches "Such a Neat Thing"

For their study, Loewy and colleagues collected rocks from a region known as the North American Mid-continental Rift System.

The system is an ancient volcanic zone running from Canada to Texas, where what is now North America started to tear apart 1.1 billion years ago. The southern end of this rift includes the Franklin Mountains near El Paso.

The team then compared the North American rocks to samples from mountains in Coats Land in East Antarctica, on the coast of the Weddell Sea (map). The Coats Land mountains are mostly buried in ice, except for "two tiny tips of mountain peaks," Loewy said.

Rocks collected from both sites match in age and in lead isotope ratios, Loewy said, showing that both sets of volcanic rocks erupted from the same rift zone.

The results indicate that, even though the regions today are widely separated, the two landmasses were once connected.

"It's such a neat thing," she said, referring to the past ties between the West Texas desert and Antarctica's glaciers. "It's a quite spectacular contrast."